The manufacture of certain products, such as roof shingles, or other generally planar products, include a conveyor that moves the product, such as a length of material, through various manufacturing stages. In the case of manufacturing roofing shingles, a felt strip is treated and adhesive material and granulated particles are applied thereto. The elongate strip eventually passes through a cutter to cut the felt material into standard lengths after which a delivery conveyor transfers the cut shingles to a packaging station. The manufacturing cost for such shingles can be minimized by increasing the conveyor speed. The limiting factor for conveyor speed, in many such manufacturing processes, is at the packaging end where the fast moving product on a delivery conveyor must be stopped and stacked for packaging. Where the speed of the delivery conveyor is very high and the moving product is stopped in a short distance, the product may be damaged during the packaging operation.
One method of increasing conveyor speed is to divert every other product on the conveyer to a second packaging station. Conceptually, the provision of two packaging stations permits the conveyor speed to be doubled, without altering the product speed at the packaging station. Providing two packaging stations, however, required a diverter in which every other product on the conveyor is diverted to a secondary delivery conveyor that leads to a secondary packaging station. Usually, the secondary delivery conveyor is positioned above or below the primary delivery conveyor and the diverter diverts every other product either upwardly or downwardly to the secondary delivery conveyor.
A speed up conveyor usually follows the cutter to provide a gap between the cut products, and the diverter follows the speed up conveyor. In one form of prior art diverters, a gap is provided at the end of the speed up conveyor and before the beginning of the primary delivery conveyor leading to the primary packaging station. The belts move with sufficient speed to provide enough kinetic energy to the product to cause it to span the gap from the speed up conveyor to the primary delivery conveyor and every other product is allowed to span the gap. The diverter includes a wheel that is pivoted downward from above into the gap that nudges every other product to the secondary delivery conveyor below the primary delivery conveyor thereby diverting every other product.
In another prior art diverter positioned after a speed up conveyor includes a plurality of spaced apart belts. A plurality of moveable ramps are intermittently projected between the belts and intercept every other product moving across the spaced apart belts. When the ramps are projected between the belts, the succeeding product is moved upwardly along the ramp to a secondary delivery conveyor positioned above the primary delivery conveyor. When the ramps are withdrawn, the alternate product is moved to the primary stacking station.
Although the diverter makes possible the use of a secondary packaging station, the diverter mechanism requires time to operate and as a result products that are to be separated by the diverter must be sufficiently spaced on the conveyor to permit the diversion mechanism to be moved in place before the arrival of the next product. In order to provide the desired spacing between products, it is often necessary to provide a series of speed up conveyors. The provision of accelerating conveyors, however, increases the space requirements of the conveyors and increases the product speed that must be decelerated prior to packaging. It is desirable, therefore, that the diverter require a minimum amount of spacing between adjacent products to thereby require a minimum increase in product speed and a minimum lengthening of the conveyor.
It is common to use servo motors in diverters because of the accuracy with which they can be controlled and the rapidity of their movements. Even so, existing diverters require that the diversion elements, such as ramped surfaces or wheels that redirect a moving product from a primary delivery conveyor to a secondary line be moved into place after the trailing edge of a first product has passed and prior to the arrival of a leading edge of the next product. Similarly, after a second product has been diverted to a secondary delivery conveyor, the ramps or wheels that diverted the second product must be removed from position after the trailing end of the second product has passed and before the leading edge of the third product arrives. The time required to insert or remove a diversion element is short; however it significantly increases the gap required between two successive products. It would be desirable therefore, to provide a short gap diverter for which no time would be required to inject the diverting elements following the passage of the trailing edge of a first product and prior to the arrival of the leading edge of a second product onto the diverting device. In such a case, the gap between successive products need not be any longer than the length of the working parts of the diverter.